Post on 30-Apr-2018
Avoka Transact Architecture Reference V4.0
© 2014 Avoka Technologies Pty Ltd. Page 2 of 7
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Avoka Transact Architecture Reference V4.0
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Avoka Transact Reference Architectures
Avoka Transact supports the creation of highly available and performant solutions deployed onto on-
premise infrastructure.
This document provides Avoka Transact Reference Architectures for High Availability (HA) solutions.
Single Data Center HA Reference Architecture
The Single Data Center High Availability Reference Architecture is illustrated in the diagram below. This
deployment model has two Transact Server nodes providing a high performance and fault tolerance.
Avoka Transact uses an essentially stateless scale-out architecture enabling:
fault tolerance fail over between Transact server nodes
schedule maintenance without service interruption
scale out performance by adding additional Transact server nodes
With Avoka Transacts’ stateless architecture the only information stored in the servers memory is the
user’s authenticated session. All transaction state is stored in a high availability SQL database.
Avoka Transact Architecture Reference V4.0
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Failure Modes
Loss of Transact Server Node
If an Avoka Transact server node fails, the Load Balancer will simply redirect the user requests to the
alternative Transact server node. If the user’s transaction requires authenticated, they will be asked to
login again but other than that they will continue their transaction seamlessly.
Transaction Performance
On recommended infrastructure 2 Avoka Transact server nodes can support 50K transactions per hour (1).
Dual Data Center HA Reference Architecture
The Dual Data Center High Availability Reference Architecture is illustrated in the diagram below. This
deployment model has two active data centers each with two active Transact Server nodes.
This architecture will ensure service continuity even in the event of losing one data centers.
In this deployment architecture a Load Balancer in front of the Data Center A and Data Center B will
balance traffic between the data centers. In this architecture the front Load Balancer will need to support
sticky sessions.
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Failure Modes
Loss of Data Center
If one Data Centers goes offline the front Load Balancer will direct traffic to the other Data Center.
Loss of Transact Server Node
If one of the Avoka Transact server nodes fails the Data Center Load Balancer will direct the traffic to the
other Avoka Transact server node in that Data Center.
Loss of Primary Database Server
If the Primary Database Server fails, the Secondary Database will be elected to become the Primary and
Transact Servers nodes will continue to function using the new Primary Database server.
Please note to support this deployment model requires low latency connections between the two data
centers to ensure high performance, and should include redundant networks. This deployment
architecture generally also requires a third monitoring site to mediate the election of the new Primary
Database server in the event of a failure.
Transaction Performance
On recommended infrastructure 4 Avoka Transact server nodes can support 100K transactions per hour (1).
Avoka Transact Deployment Requirements
To support these High Availability deployment architectures Avoka Transact requires:
Load Balancing Switch with sticky session support (JSESSIONID cookies)
VMware Host servers (or physical servers with CentOS 6 or Microsoft Server 2008R2-2012) for
the Avoka Transact server nodes
Virtualized Avoka Transact server nodes are deployed in separate availability ‘zones’ to
minimize single points of failure, i.e. separate physical servers, separate power supplies, etc.
SQL database with high availability support (Oracle 11g, Microsoft SQL Server 2008-2012,
Oracle MySQL 5.1-5.5)
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Avoka Transact Server Node Requirements
The server requirements Avoka Transact nodes include:
Processors Intel Xeon Processors (8 Cores) with 2.4 GHz or greater clock speed
Memory 12 GB of RAM
Storage 100 GB of disk storage
Performance Caveats
(1) Performance estimates are based on:
system load testing and real world experience,
Avoka Transact deployed on the servers meeting the specified requirements,
standard Avoka Transact server configuration,
transaction using a medium size 6 page HTML form, with landing page and confirmation page
transaction flow,
transaction includes rendering a PDF receipt document,
use of a Content Distribution Network (CDN) to serve static content, and
transaction throughput not being limited by network constraints or SQL database performance.
Please note system performance will vary significantly depending upon the type of user load (network
latency, user bandwidth and concurrent sessions) and the size of the form and content rendered.
If the form transaction does not require a PDF receipt to be rendered then transaction throughput will be
substantially higher (in excess 2X).
Use of a CDN to serve cacheable static content improves transaction throughput by approximately 20 to
30%. Avoka Transact supports the Akamai, Amazon CloudFront and CacheFly CDNs.
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Alternative Web Server Deployment Model
Some organizations security policies may require Apache Web Servers to be deployed onto separate
servers from the Avoka Transact server nodes.
While this is not our recommended deployment model Avoka Transact fully supports this architecture.
Please be aware this deployment model incurs additional cost and effort to commission and maintain.
Further Information
If you want to know more about Avoka Transact solution architectures, please contact sales and they can
organize a discussion with a Client Services Engineer.
Please also see the following documents for further information:
Avoka Transact Platform Support
Avoka Transaction Manager Installation Guide